Full Idea
Davidson's version of the identity theory is couched in terms of events rather than states, because he regards causation as a relation between events.
Gist of Idea
Davidson sees identity as between events, not states, since they are related in causation
Source
report of Donald Davidson (Mental Events [1970]) by E.J. Lowe - Introduction to the Philosophy of Mind Ch.2 n12
Book Reference
Lowe,E.J.: 'Introduction to the Philosophy of Mind' [CUP 2000], p.33
A Reaction
I think it may be more to the point that the mind is a dynamic thing, and so it consists of events rather than states, and hence we want to know what those events are made up from. I think my chair is causing me to rest above the floor…